The 4th-generation (4G) communication system, which is a future communication system, is advancing to providing users with various services such as broadcasting, multimedia video, and multimedia message. In particular, the future wireless mobile communication system is developing to offer data service over 100 Mbps to a user moving fast and data service over 1 Gbps to a user moving slowly. Its representative communication system is an Institute of Electrical and Electronics Engineers (IEEE) 802.16 system. The IEEE 802.16 system employs an Orthogonal Frequency Division Multiplexing (OFDM)/Orthogonal Frequency Division Multiple Access (OFDMA) scheme to support a broadband delivery network in a physical layer.
The broadband wireless communication system should be able to support terminals of different available bandwidths and to operate a plurality of frequency bands in one or more frequency spectrums as well. To transmit and receive signals in the various bandwidths or the multiple frequency bands, a multicarrier scheme or a frequency overlay scheme can be adopted. Herein, the multicarrier scheme or the frequency overlay scheme transmits and receives signals over the different bandwidths or one or more frequency bands at the same time.
FIG. 1 illustrates the division of the frequency band into a plurality of subbands at a base station of the broadband wireless communication system to support terminals of different bandwidths. In FIG. 1, given a terminal A 110 with one Frequency Assignment (FA), a terminal B 120 with four FAs, and a terminal C 130 with two FAs, the terminal A 110 uses FA#2, the terminal B 120 uses FA#1 through FA#4, and the terminal C 130 uses FA#2 and FA#3. However, the terminal A 110 can selectively use one of FA#1 through FA#4, rather than using only FA#2. The terminal C 130 can use any two of FA#1 through FA#4. According to capability of the terminal, two consecutive or discontinuous FAs may be used concurrently. Accordingly, the base station 150 needs to suitably regulate the FAs used by the terminals by taking into account the bandwidth use capability of the accessed terminals. The base station 150 transmits and receives signals by allocating one or more FAs based on the bandwidth (the band processing capability) of the terminals.
As discussed above, in the broadband wireless communication system supporting the frequency overlay, the base station needs to provide a synchronization signal for time, frequency and frame synchronization and system acquisition information required for connections to each terminal. Simultaneously, the base station 150, which supports the terminals using the different FAs concurrently, needs to transmit the synchronization signal and the system acquisition information in every FA. However, since the synchronization signal and the system acquisition information exclusively occupy resources from traffic data, the redundant transmission of the synchronization signal and the system acquisition information lower the system capacity. Therefore, what is needed is a method for reducing overhead caused by the synchronization signal and the system acquisition information.